Modern motor vehicles are frequently equipped with an optical sensor device to detect moisture on an outer surface of the glass windshield, which is coupled with a control device for controlling a windshield wiper system of the glass windshield so that the wiping processes are able to be controlled automatically as a function of the degree of wetting of the glass windshield. Such optical sensor devices—generally designated as “rain sensors”—are used in practice in numerous variants and have already been described in many cases in the patent literature. They are based on the fundamental principle that the glass windshield serves as an optical waveguide. The light generated from an optical transmitter is coupled in on the inner side of the pane facing the passenger compartment and after total reflection on the outer side of the pane, facing away from the passenger compartment, is coupled out on the inner side of the pane and is picked up by an optical receiver. Depending on the degree of wetting of the outer surface of the glass windshield, which involves a change to the refractive index for the pane/air transition of the outer side of the pane, the proportion of the reflected light varies, so that indirectly a conclusion can be drawn as to the quantity of fluid or respectively the degree of wetting on the outer surface of the glass windshield.
On the one hand, rain sensors must be arranged in the wiping field of the glass windshield, but on the other hand they must at least not substantially impair the clear visibility for the driver. Usually, rain sensors are mounted for this purpose in the region of the interior rear-view mirror on the inner side of the glass windshield. In addition, in this case, the portion of the electric leads situated in the region of the glass windshield for supplying the rain sensor with electric power and for signal transmission to the control arrangement of the windshield wiper system can be kept relatively short.
In motor vehicles with composite panes, which typically have an outer and inner pane with an intermediate layer of, for example, polymer material, the light is coupled in on the inner side of the composite pane facing the passenger compartment, passes through the intermediate layer, and after total reflection on the outer side of the outer pane is coupled out again on the inner side of the composite pane.
In contrast, at least one object is to provide an improved composite pane arrangement. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.